Shape Memory Performance of Epoxy Resin-Based Composites

1. ShapeMemory Performance of EpoxyResin-BasedComposites JózsefKarger-Kocsis, Márta Fejős Budapest University of Technology and Economics Department of Polymer Engineering E-Mail: karger@pt.bme.hu

2. Outline • Introduction • Motivation • Possibleapplications • Properties of shapememoryepoxy • Properties of shapememoryepoxycomposites • Futureworks

3. Introduction Materials Non linear, Reversible Material’s property Functionalmaterials Structuralmaterials Ttrans Smartmaterials Smartmaterials Environmentalcondition (Temperature) Shapememorymaterials Shapememoryalloys Shapememorypolymers

4. ShapeMemoryAlloys Parentphase T Af Ms Stress, σ[MPa] 4 1 As Mf σ 3 2 4 1 2 3 Strain, ε[%] T[°C] Martensitephase

5. ShapeMemoryPolymers T σ σ[MPa] σ 4 Ttrans 4 1 2 3 ε[%] 3 2 T[°C] 1

6. Schematic Architecture of SMPs J. Hu, Y. Zhu, H. Huang and J.Lu. Progr.Polym.Sci. 37 (2012), 1720

7. Basic Differences Between SMA and SMP P. Ghosh et al.: Mater. Design 44 (2013), 164-171

8. Motivation • Toincreaserecoverystresswithoutloosingthedeformability • Attemptswithepoxyresinbasedcomposites

9. ShapeMemoryEpoxyResin – Mechanism and Properties T<Tg T>Tg T<Tg T>Tg after T<Tg Ttrans=Tg • Excellentshape fixity and shape recovery properties (>95% each) • Good environmentaldurability (essentialforspaceapplications) • Good adhesiveproperties (matrixmaterialinpolymericcomposites)

10. PossibleApplications of ShapeMemoryEpoxyComposites Solararray Deployablespacestructures Reflector J. Lenget al.: ProgressinMaterial Science56, 2011, 1077-1126

11. ShapeMemoryProperties - Unconstrained (Free) Recovery Rf [%] shapefixity ratio Rr[%]shaperecovery ratio RΣ [%] shapememory ratio ε0 [%] originalshape εm [%] requiredtemporaryshape εu [%] fixed temporaryshape εp[%]recoveredshape Ts [°C] storagetemperature Tg [°C] glasstransitiontemp. Td [°C] deformationtemp. σmin [MPa] preloadstress σload[MPa] deformationstress εm Td εu Strain, ε [%] Temperature, T [°C] Tg Rf RΣ Rr εp Stress, σ [MPa] σfix σload Ts σmin Time, t [min] ε0 • Temperature, stress and strainhaveto be determinedas a function of time • Universaltensiletester • Dynamicmechanicalanalyser • Deformationmodes • Tensionorcompression • Flexure • Torsion

12. ShapeMemoryProperties - ConstrainedReheating εm ε0 [%] originalshape εm [%] requiredtemporaryshape Ts[°C] storagetemperature Tg [°C] glasstransitiontemp. Td [°C] deformationtemperature σmin [MPa] preloadstress σload[MPa] deformationstress σrec[MPa] recoverystress Td Strain, ε [%] Temperature, T [°C] Tg Stress, σ [MPa] σfix σload σrec Ts σmin Time, t [min] ε0 • Recovery stress determined in fully constrained reheating • Recovery stress is equal to the deformation stress, if no damage occurred in the specimen. Therefore recovery stress can be estimated from „traditional” unconstrained tests, if stress is measured.

13. ShapeMemoryPerformance of Epoxy/GlassFiberFabricComposite • Strainatbreak [%] • E-Glassfibre ~2.5 • Carbonfibre ~1.6 • Aramidfibre ~3.5 • Flaxfibre ~2.9 2 3 4 4 3 2 1 1 1 2 3 4 Deformation Fixation Recovery Unload M. Fejős, G. Romhány, J. Karger-Kocsis: Journal of ReinforcedPlastics and Composites 56, 2012, 1532-1537

14. Asymmetric Shape Memory Epoxy/Carbon Fiber Fabric Composites • Carbonfibre has negativethermalexpansioncoefficient, whichincreasestheasymmetry • Asymmetricsamples show bucklingupontemperaturechange, because of thedifferentthermalexpansioncoefficientofthelayers. M. Fejős, J. Karger-Kocsis: Express PolymerLetters 7, 2013, 528-534

15. AsymmetricShapeMemoryEpoxy/CarbonFiberFabric Composites – UnconstrainedShapeMemory Test EPCF2t EPCF2b σcontrol εcontrol σcontrol εcontrol Basedonbending test: εm=2.5% M. Fejős, J. Karger-Kocsis: Express PolymerLetters 7, 2013, 528-534

16. AsymmetricShapeMemoryEpoxy/CarbonFiberFabric Composites – ConstrainedShapeMemory Test EPCF2b EPCF2t M. Fejős, J. Karger-Kocsis: Express PolymerLetters 7, 2013, 528-534

17. ELO BasedFlaxFiberFabric-ReinforcedBiocomposites Twill (T) 420 g/m2 Nonwoven (NW) 220 g/m2 Quasi UD 420 g/m2 Quasi UD 275 g/m2 • Matrix: Epoxidized linseed oil (ELO) cured by stoichiometric amount of methyltetrahydrophthalic anhydride (Aradur 917 CH), accelerated by 1-methylimidazole (both from Huntsman Advanced Materials). • Textile conditioning: Drying at least 3 hours at 80°C, prompt impregnation. • Applied pressure and temperatures: 8 MPa; 2h 100°C, 2h 140°C and 2h 180°C. : M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of ReinforcedPlastics and Composites 32, 2013, 1879-1886

18. ELO BasedFlaxFiberFabric-ReinforcedBiocomposites - DMTA • The higher the fibre content the lower the Tg, because remaining water and • hydroxil groups react with anhydride hardener. M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of ReinforcedPlastics and Composites 32, 2013, 1879-1886

19. ELO BasedFlaxFiberFabric-ReinforcedBiocomposites – ShapeMemory Performance • Naturalfiberslowernotonlytheshapefixity, butalsotheshaperecovery ratio (discontinousfiber) • ELO matrix is „weak” (lowcrosslinkdensity) M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of ReinforcedPlastics and Composites 32, 2013, 1879-1886

20. Summary • Reinforcements is associated with reduced shaping freedom. • Damage starts at the compression side of the specimen in flexure, but microbuckling can be exploited for shape memory. • Asymmetrical reinforcement may support the shape memory if suitable fibers are positioned at the tension side of the specimen. • Shape memory strain and recovery stress can be simultaneously increased with proper asymmetric fabric (hybrid) arrangements.

21. Recommendations for Future Works • Torsion as loading mode needs special attention • Aramid fibers arepromisingcandidates. • Assessment of damage in shape memory cycle is essential for development of shape memory epoxy composites. • Because natural fibers can change the matrix’ Tg locally, multishape memory composites can be made.

22. Thank you for your attention.